1. Field of the Invention
The present invention is an anti-dead locking, anti-vibration, and loosening-proof bolt and nut structure taking advantage of the spring nature of an external threaded sleeve and an internal threaded lining in cooperation with relative movability after engagement of a plurality of axial teeth and engaging internal teeth. The bolt and nut structure is used for a locking environment where a bolt and a closed screw connection threaded hole or a nut are to be assembled. The structure has effects such as vibration absorption (i.e., anti-vibration), anti-dead locking and breakage resistance.
2. Description of the Prior Art
The conventional locking technique of a bolt (or screw) and a nut includes principally external threads and internal threads provided respectively on the shank of a bolt and a nut. Rotational engagement of the external threads and the internal threads creates an axial clamping or course guiding action. Various threads, no matter whether they are the conventional triangular, square or trapezoid threads, can convert the twisting force created by rotating a screw or a nut into an axial locking thrust by a frictional pushing force between the threads mutually engaged. Therefore, tight screw connection between the locking members under normal conditions can be effected. However, many screw connection situations are subject to vibration. Examples are a screw connection of mechanical transmitting components between a transmission axle and a wheel rim on a car, on the housing of an airplane, on a tunnel drilling machine with high vibrational frequency, on an oil drilling machine, a pile driver, an engine, an air compressor, an oil compressor, etc. When vibration is present, the screw connections are subject to loosening or breaking.
When threads are mutually engaged, the sets of threads must have therebetween a tolerance to allow rotational advancing of the threads. However, the tolerance prevents the surfaces of the threads from being in complete contact for giving a frictional pushing force. In other words, after the components are joined, the surfaces not in contact due to the tolerance make the twisting force for resisting loosening by friction on each thread surface unable to withstand the vibrational force from the exterior so that loosening occurs. The rigidity provided by the engagement of the threads tends to generate shearing force, and the screw or bolt can be broken to induce a dead locked state.